Overloading and slack cable-stop for electrical hoisting-machines



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CVEELOADING AND SLACK CABLE STOP FOR ELECTRICAL HOISTING MACHINES.

No. 394,952. Patented Dec. 25, 1888.

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, W. BAXTER, J1. CVEE'LCADINC AND SLACK CABLE STCE ECE ELECTRICALECISTINC. MACHINESE No. 394,952. Patented DCC. 25, 1888.

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www Mg/f UNITED STATES PATENT GEEicE.

XVUATIAM BAXTER, JR., OF BJJITDORE COVNTY, MARYLAND.

OVERLOADING AND SLACK CABLE-STOP FOR ELECTRICAL HOISTING-MACHlNES.

SPECIFICATION forming part of Letters Patent No. 394,952, dated ecember25, 1888.

To all whom it' may concern.' l

Be it known that l, \\.'ILLIAM BAXTER, J r., a citizen ot' the UnitedStates, residing in the county of Baltimore, State of Maryland, l haveinvented certain new and useful lmprovements in Overloading and SlackCable- Stops for Electrical l-loisting-Machines, ful-ly i described andrepresented in the following l specification and the accompanying draw`ings, forming a part of the saine.

rlhis invention relates to that class of hoistl ing-machines in which anelectric motor used for actuating the hoisting mechanism, and thehoisting car or platform is elevated t (by such mechanism) ina verticalor inclined hoistway; and the object of this invention is to provide anysuch hoistingmechanism with means for stopping the electric motorautomatically when, on the one hand, the car is overloaded, or, on theother hand, when the y car or its eouiiter-balance is obstructed, sothat the hoisting-rope becomes slack or overstrained.

It is well known that in electric motors operated at a constantpotential the current passing' through the motor increases with the Iresistance opposed to .its rotations, and the overloading` of thehoisting mechanism, which would impose upon the motor a resistancegreater than its normal capacity, would therefore tend to increase thecurrent to such an extent as to burn out the armature and to 5 thus ruinthe machine.

My present invention provides an electric switch which is operatedautomatically by the movement of some support which sustains the weightor pressure oi' the ear, and which is adapted to yield when the car iseither overloaded or obstructed.

My invention also includes an automatic indicator, as a bell, operatedby a yielding connection with the car when overloaded, to warn theconductor that a portion oli' the load 1 must be removed, an electriccircuit being derived from the main motor-circuitor from a local batterycarried upon the moving' ear i or platform to actuate the indieatonif amagl netic device be used. The yieldingI support, aifected by thevariable load in the car, must l ot' necessity be located between thehoisting device and the car-platform, and may therefore be combined witha pulley-bearing, over ry 28,1888. Serial No.265,575. (No modela whichthe hoisting-ropeis conducted, with an elastic connection between thecar and its l suspemling-rope, or with. any other element of thehoisting device which is affected by the load imposed. It' the hoistingmechanl ism continues to pay out the suspending-rope when the car isobstructed in its downward motion, such rope is liable to be greatlyderanged when again wound up, or is liable to rupture it the obstructionto the car be suddenly removed and the car allowed by the slack in therope to fall a considerable distance. Then a counter-balance is used andconnected with the car by a rope, the evils arising' from an obstructionof the counterbalance are nearly as great as those affecting the car,and my appliances are equally applicable for automatically stopping theelectric motor when the counter-balance is obstructed in its movement,so as to slaeken or tighten its suspending-rope.

My improvements will be undcrstmid by reference to the annexed drawings,in which- Figure l is a diagram of an electric motor actuating ahoisting apparatus, the drum of which is connected by a rope with asuspended ear, and the motor-circuit conveyed to the car by a cable toactuate an electric indicator therein. The circuit in this ligure isarranged to operate with constant potential y an independent batterywith a local circuit,

also indicated in dotted lines within the car. Fig. 2 is a diagramshowing a yielding bearing for the counterbalance-pullcy, a motorcircuitadapted to operate with constant current, and an electric switchactuated by the y movement of the yielding bearing to shortcircuit suchmotorwhcn the car is overlmnled. l, l-, and 5 show constructions lforthe yielding-car connection. Fig. o is a diagram of the constantpotential switch with circuit opened.

ln Fig. l, ll is a ln)isting-machiiic actuated by electric motor 3l. Pare the posts of the hoistway; P', a beam across the top, supporting` acountei-balaiice-pulley, l, and two guidepulleys, .l and K, leading thehoisting-rope L from the hoister-drum to the car A counter-balance, (f,is connected with the car by a rope, C2, passed over the pulley I. Apulley, N, is arranged below the level of the hoisting-drum to guide therope L downward TOO 2 v scesa from the la-tter to illustrate theapplication ot' a yielding bearing to sustain an upward pull. The motoris connected with an electric circuit by wires w i', the current beingconnected with switches s, s', and s?, which are actuated, respectively,by thc bearings ot' the pulleys K, N, and I. The conductors r 1c arealso connected through a iiexible cable, Q, to a switch, S3, inside thecar, which is actuated when the car is overloaded to operate a suitableindicator and notify the attendant that it would be injurious to startthe motor. Such switch is moved by a yielding connection between the carand its suspending-rope, and is thus affected by the load placed uponthe car-platform. The yielding connection consists in a sliding` bolt,l), fitted through the roof of the car, with a head, d, upon its innerend and a spring, b, inserted between the head and the car-beam b. Therope being attached to the outer end ot the bolt, it is evident that theload placed upon the car-platform p would operate to compress the springand move the head d toward the top of the car. A bell, g, is shown fixedwithin the car, with a magnet, G, to actuate its hammer g electrically.

e e are the terminals of the circuit-wires, conducted to the car throughthe cable Q, and are formed as springs, one of which is arranged in thepath of the bolt-head d, to be moved when the spring l) is abnormallycompressed.

The springs@ c are mounted upon a switchbase, s3, to adjust the spring cin such relation to the bolt-head (l that when the proper load upon theplatform of the car is exceeded it will be pressed against the spring eand the circuit closed through the bell-magnet G to operate the alarm asdesired.

The use of a bell serves to call the operators attention more vforciblythan an inde-.vhand upon a dial; but it is obvious that any form ofannunciator may be operated by the circuit, when closed, through thesprings c e. It is also obvious that a local battery carried within thecar maybe used instead of abranch of the motor-circuit, and such batteryis indicated at q, with dotted connections 102 and w3, leading,respectively, to the magnet G and the spring c, like the terminals ofthe wires it w.

Three different forms of yielding bearing are shown in connection withthe pulleys l, K, and N, that for the pulley l consisting in a pedestal,B, having one end of its foot resting upon a spring, t, adapted to yieldwhen the normal pressure upon the pulley-shaft B is varied. The otherend of the pedestal-foot is connected with its supporting-beam P by ahinge, B2, and the movable end of the foot is connected by a pin, c,with a switch-lever, c. The switch-lever is actuated by the movement ofthe foot to open the circuit and stop the motor when the counter-balanceis obstructed in its movement, so as to sufficiently vary the pressureupon the .bearing B.

The movable end of the switch operates normally to imite two contacts,d", to maintain a closed circuit, as shown in l, and the weight of thecar and counter-balance operate normally to compress the spring t to thepoint at which the switch is adjusted to close the circuit. The switchis therefore adapted to open the circuit and stop the motor ii' movedineither direction, and an obstruction to the counter-balance in itsdownward movement, which would tend to slacken the pressure upon thebearing li, thus permits the spring t to raise the movable end of its'toot and move the switch with the same effect as when the pressure uponthe bearing was increased. As the ropes pass over the pulley K in ahorizontal and vertical direction, the resultant pressure is at an anglewith both ropes, and the boxf, supporting the pulley-axle K', is shownguided in an inclined socket provided with a pin to actuate aswitch-lever, c', as just described. To sustain the box against thepressure ot the rope, a bent lever, j", is pivoted upon the pulley-standand coupled with the box by link Z. rlhe lever is provided with slidingweight f2, which' is adjusted to balance the proper load, so as to holdthe switch in its neutral position to close the circuit between thecontacts d. The metallic connection c'2 between the blocks d is lappedupon each far enough to permit a normal movement of the bearing f and Bwithin the limits ot an ordinary load without breaking the connectionbetween the blocks and stopping' the motor; but an obstruction to thecar in its downward movement would diminish the pressure upon thebearing and break the circuit by moving the switch in one direction,while an overload upon the car would cause the breaking of the circuitby moving the switch in the opposite direction, as described for thebearing i3.

The bearing for the pulley il is formed at the end of a hinged arm,N,witha spring, n2, above the bearingI to allow ot its vi elding likethose last described.

The switch c is connected with the bearing by a pin, as in the otherconstructions, and the circuit through the motor is connected in serieswith its contact-blocks d', so that the circuit may be broken by asuitable movement of the switch.

ln Fig. 2 is shown the construction for the switches to operate withconstant current, and a cut-out switch is shown. within the carto beactuated by the bolt-head d with either a slack-cable or overload forcutting out the motor and stopping the hoisting mechanism automatically.The switch is the same as that shown at the upper part of the figure,actuated by the yielding pulley bearing over which the suspending-ropeis carried, and the motor for operating the hoisting mechanism is merelyindicated with its operative circuit, as my improvement relates only tothe electrical connections. The motor circuit is shown in the wires atd5, connected with the positive and negative line-wires, and the? twoIOO IIO

switches are adapted to make a connection in a loop ot' the saidcircuit, and to thereby short-circuit the motor and cause its immed iatestoppage when either switch is operated. The switeh-lever in the car isshown actuated by a pin7 d, upon the bolt-head d, so that the movementof the. bolt-head will actuate the switch-lever the same as the movementot the yielding-bearings heretofore described.

Each switch is provided with two contacts, o', both connected with thesame circuitwires o?, and the other circuit-wire7 (ri, is connected witha metalli e piece, o, upon the switch-lever c. The piece or block o. isnormalty Separated from the contacts o with a space between Such partssut'tieient to allow the movement of the lever e within the normalvariations ot the load, while any variations above or below the normalwould move the block u desired.

It is obvious that either ot' the switches i illustrated would etteetthe desired object, l

and that both would not be required in the lsame construction, thedrawings being;l t'urnished with both the switches mel'elyto illus tratea variety ot' applimitiions.

The circuitis conveyed to the car through two conductors, d"e and di",shown, t'or convenience, fixed at opposite sides ot the carin thehoistway, with brushes or contacts dl sliding' over them with themovement of the car, and the circuit-wires u? and u connecting' suchbrushes with the contacts u in the earswitch.

it; is obvious that the current could be coitveyed to the ear by acable, as shown in Ifig. l, or by any other suitable means. Theindicator or bell (shown `in Fie'. l) would pret"- erably be set to giveits alarm with a somewhat lighter load than that required to oper-i ateany ot the motor-switches shown applied to the yielding' bearings, so asto give warning' to the operator in time toavoid the actul ation ot suehswitches.

lt an automatic motor-switch were not ear or contiter-balance whenascending' would l not operate directly to stop the motor, but it wouldcontinue its revolution until its t'oree l were balanced bythe strain onthe ropes, and this strain might be sut'licient to do serious damage lothe mechanism.

VWhere iron orsteel ropes are used their entang'lement or winding' overoneanother upon the drum causes short bends and intlicts serions injuryttpon them; but such injuries may be wholly avoided by a suitableadjustmentot the devices shown herein to etiect the stoppage ot themotor betore the ropes become slack enough to leave the grooves in thedrum.

lt is obviously immaterial what means are employed to balance thetension upon the` yielding' bearing' orsuspemlinir-riuie, provided thepressure or weight ot' the car be sustained into contact with one ot."the pieces o', and thus short-eireuit the motor, as

Y provided, any obstruction to the nit'ivement ot' the at some pointbetween the hoisting' device and car-platform by a yielding' supportadapted to move an electric switch in the manner set forth.

The operation oit' the switches with j-onstant1 current and constantpotential cireuits is substantially opposite, as is common with such icircuits, the motor being' stopped in the one l ease byshort-circuitingI and in the other b v opening the circuit; but theautomatic switches may be made ot' any etmstrtn-tion adapted to controlthe movements ot' the eleotrie motor and hoisting' nteeltanism. asdesired.

. It is obviously immaterial how the power of the motor be applied tomove the load. as g the connection between the motor and the carfplattform would in any case at'tord an oppori tunity for the insertionot a yielding' support to aetuate a switch, as required in my inven ltion. l It will be noticed, although several ditlierent constructionsfor the automat ic swit eh are "shown in Fie'. i, that in practice asingle switch at any convenient point in the circuitV is all that wouldbe required. and the arrangement ot the several swit '-hes in series inthe diagram is shown only to illustrate their mode of operation andwould not be required in practice. lt will be also understood that theparticular construction t'or the yielding' bearing' is immaterial, andthat a weight, a spring', or any other suitable resistance may beopposed to the load upon the rope to hold the bearing' and switchnormally in a position to operate, as desirial. lt is also immaterialhow the yielding' connection to the earbe constructed, and I have shownin ldig's. il. -t, and 5 a variety ot' such constructions toillustrati'A the scope ot` my invention. llaeh otI these yielding'connections is shown operating' a switch conneeted with the terminals otan electric circuit, and sneh circuit may be em i ployed either to stopthe motor or to operate a bell or indicator, as may be desired.

lu liir. if) the rope l'. isattaehed to the short arm ot a lever, L',pivoted upon the top ot' 1 the car, and a weight is eonnmft'ed with thelong' artn ol the lever to eounterlalanee the pull on the rope to acertain limit. 'lhe end ot` the lever is linked to a multpIyng-lever,el, connected with a pneumatic bell-push, e", the bell c being' `shownjust below it, and the f excessive load upon the ear would operate tomove the leverand aetuate the bell-push and i bell, as desired. l inFig'. -t the rope 'l'. is shown passed bet two guide-pulleys, Il, whichare pivoted upon a t'rame, m, adapted to turn upon the top ot the earand to strain the suspending-rope out ot its normal vertical position.The tension upon the pulleys is produced by a springt/1, l t

attached to the top ot the car and to the i, trame nl, and operatesnormally to bend the rope in a certain degree until the load upon I thecar becomes excessive. rThe frame is linked to a switch, c', and suchexcessive load lOO llO

y of a yielding' support sustaining the pressure device operatedthereby, and a moving car is shown operating, by straining the rope L,to tip the frame against the tension of the spring and to shift theswitch as desired.

In Fig. 5 the rope l) is connected with the top of the car through themedium of a couple 1 of toggles, which are attached at their ends to thecar and to the rope, a spring, n", being inserted between them to presstheir middle joints apart. Any excessive tension upon the rope operatesto-comprcss the spring' and to move an arm, n, connected with one of thetoggles and to a switch, f", snitablel'or a constant potential circuit.

ln any of these constructions a weight or spring may be used atpleasure, or any other suitable means may be employed to 4perform thesame function.

Any of the yielding'bearings or connections shown herein may obviouslybe einployed to actnate the indicator or bell by other mechanical meansthan a pneumatic bell independently of an electro-magnet.

Having' thus set forth my invention, whatl cla-im herein is-d l. In anelectrica-l elevator system, the combination, with an electric motor, ahoisting device operated thereby, and a moving' car suspended by a ropefrom a hoisting device,

of the rope between the hoisting' device and the car-platform and anelectric switch in the motor-circuit actuated by the movement of suchyielding support to stop the electric motor.

In an electrical elevator system, the combination, with an electricmotor, a hoisting device operated thereby, and a moving` car suspendedby a rope from the hoisting device, of a pulley sustaining the pressureof the rope, a movable or yielding' bearing` for supporting thepulley-axle, and an electric switch actuated by the movement of thebearing to stop the electric motor, as and for the purpose set forth.

3. In an electrical elevator system, the combination, with an electricmotor, a hoisting' device operated thereby, and a moving car suspendedby a rope from the hoisting device, l of a pulley sustaining thepressure of the rope, j a movable or yielding bearing' for sumiortingl lthe pulley-axle, a springer weight adjusted to sustain the bearing undera given load, and an electric switch actuated by the movement of thebearing' to stop the electric motor when such load is exceeded.

i. In an electrical elevator system, the conibination, with an electricmotor, a hoisting' suspended bya rope from the hoisting` device, of apulley sustaining' the pressure of the rope, l a movable or yielding'bearing' forsupporting the pulley-axle, and an electric switch actuatedby the movement of the bearing' to close i a short circuit around themotor, as and for the purpose set forth.

` 5. In an electrical ele va-tor system, the combination, with anelectric motor, a hoisting device operated thereby, and a moving carsuspended by a rope from the hoisting device, of a pulley sustaining`the pressure of the rope, a movable or yielding bearing for supporting'the pulley-axle, a counter-balance connected with the car by a suitablerope, a pulley with yielding' bearing' for sustaining said rope, andelectric switches applied to both of said yielding' bearings forstopping' the motor, substantially as herein setforth.

o'. ln an electrical elevator system, the combination, with a suspendedcar, of a yielding' connection between the car and its suspendin g-rope,an electric circuit connecting' the car with the electric motor, and aswitch in such circuit upon the car, actuated by said yieldingconnection to stop the motor when the car is obstructed in its movement.

7. The combination, with a hoisting device and a moving car suspended bya rope therefrom, of a yielding support sustaining' the pressure of therope between the hoisting' device and the car-platform, and a bell orindicator actuated by the movement of such yielding support, as and forthe purpose set forth.

8. In an electrical elevator system, the combination, with a suspendedcar, of a yielding' connection between the car and its suspending-rope,a magnetic bell or indicator, an electric circuit for operating thesame, and a switch arranged in said circuit and actuated by the yieldingrope-connection to operate the bell or indicator.

9. ln an electrical elevator system, the combination, with a suspendedcar, of a rope connected with the car by an adjustable springcoupling, amagnetic bell or indicator upon the car and an electric circuit foroperating the same, and a switch arranged in said circuit and actuatedby the spring-coupling', when the maximum load is imposed upon the car,to operate the bell or indicator, substantially as herein set forth.

l0. ln an electrical elevator system, the combination, with a suspendedcar, of a yielding connection between the car and its suspending-rope, amagnetic bell or indicator, and an electric circuit for operating thesame, alocal battery carried by the car for operating such circuit, anda switch arranged in said circuit and actuated by the yieldingrope-connection to operate the bell or indicator.

In testimony whereof l have hereunto set my hand in the presence of twosubscribing witnesses.

WM. BAXTER, JR.

Vitnesses:

L. LEE, Tiros. s. CRANE.

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